Date: Thu, 30 Mar 2006 11:06:31 GMT From: Tomas Olsson <tol@stacken.kth.se> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/95103: panic after mtx_destroy() on locked spinlock Message-ID: <200603301106.k2UB6VTC019683@www.freebsd.org> Resent-Message-ID: <200603301110.k2UBAEF0059266@freefall.freebsd.org>
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>Number: 95103
>Category: misc
>Synopsis: panic after mtx_destroy() on locked spinlock
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Mar 30 11:10:14 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator: Tomas Olsson
>Release: 5.5-BETA4
>Organization:
Stacken Computer Club
>Environment:
FreeBSD lab04.lab.it.su.se 5.5-BETA4 FreeBSD 5.5-BETA4 #0: Mon Mar 13 23:12:57 UTC 2006 root@perseus.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC i386
>Description:
MUTEX(9) man page, under mtx_destroy() says:
It is permissible to have a single hold count on a mutex when it is destroyed.
This does not seem to be the case when the mutex is a MTX_SPIN lock. I get a panic very soon after I call mtx_destroy() during kld unload unless the lock is released. Page fault in user mode seems to be a common panic "cause" for this.
With a MTX_DEF it appears to work according to docs.
>How-To-Repeat:
{
struct mtx lock;
mtx_init(&lock, "foo", NULL, MTX_SPIN);
mtx_lock_spin(&lock);
mtx_destroy(&lock);
}
(tried during kld unload)
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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